Device in the delivery of sheet-fed rotary printing machine for inhibiting curl formation in the leading edge of delivered sheet

Abstract

A delivery system of a sheet-fed rotary printing machine includes a device for inhibiting curl formation in a leading edge of a sheet, comprising blowing units disposed at a location of the delivery system whereat, as viewed in travel direction of the sheet, a forward region of a stack of delivered sheets is disposed. The blowing units are in vicinity of a location at which the leading edge of the sheet being delivered travels downwardly. The blowing units have respective means for directing a controlled air jet, with one directional component in the travel direction of the sheet and another directional component towards the middle of the sheet, against the underside of the downwardly traveling sheet in vicinity of the leading edge of the sheet tending to curl.

There are claimed: 
     
       1. In a delivery system of a sheet fed rotary printing machine having a conveyor for transporting a sheet in a given travel direction to a location of the delivery system at which a stack of sheets is deposited, a device for inhibiting curl formation in a leading edge of the sheet, comprising means for downwardly directing the sheet at the location at which the stack of sheets is deposited, and blowing units disposed at a location of the delivery system whereat, as viewed in the given travel direction of the sheet, a forward region of the stack of delivered sheets and a leading edge of the downwardly directed sheet are disposed, said blowing units having respective means located at opposite sides of the forward region of the stack and at opposite edges of the sheet adjacent the leading edge thereof for directing a controlled air jet, with one directional component in the travel direction of the sheet and another directional component towards the middle of the sheet, against the underside of the downwardly directed sheet in vicinity of the leading edge of the sheet tending to curl, said blowing units, respectively, comprising a housing block formed with a threaded bore and air outlet openings for supplying air thereto via a hose connection and a check valve, and including fastening means for fastening said housing block to a respective lateral sheet straightener, said housing block is formed as a substantially rectangular cylinder, and said sheet straightener is located at a side of the delivery, and including a bracket formed with a threaded pin projecting through an elongated slot formed in said sheet straightener, said bracket being connected to said sheet straightener by a nut threadedly tightened on said threaded pin, and further including retaining screws fixing said housing block to said bracket, said housing block having a substantially rectangular side having a beveled region wherein said air outlet openings are formed. 
     
     
       2. In a delivery system of a sheet fed rotary printing machine having a conveyor for transporting a sheet in a given travel direction to a location of the delivery system at which a stack of sheets is deposited, a device for inhibiting curl formation in a leading edge of the sheet, comprising means for downwardly directing the sheet at the location at which the stack of sheets is deposited, and blowing units disposed at a location of the delivery system whereat, as viewed in the given travel direction of the sheet, a forward region of the stack of delivered sheets and a leading edge of the downwardly directed sheet are disposed, said blowing units having respective means located at opposite sides of the forward region of the stack and at opposite edges of the sheet adjacent the leading edge thereof for directing a controlled air jet, with one directional component in the travel direction of the sheet and another directional component towards the middle of the sheet, against the underside of the downwardly directed sheet in vicinity of the leading edge of the sheet tending to curl, said blowing units, respectively, comprising a housing block formed with a threaded bore and air outlet openings for supplying air thereto via a hose connection and a check valve, and including fastening means for fastening said housing block to a respective lateral sheet straightener, said housing block is cylindrical with a circular cross section and has a threaded pin projecting through an elongated slot formed in said lateral sheet straightener, and including a lock nut tightened on said threaded pin for positively fastening said housing block to said lateral sheet straightener. 
     
     
       3. Device according to claim 2, wherein said blowing unit is slidable in said elongated slot formed in said lateral sheet straightener selectively in direction of sheet travel and opposite thereto and is fixable in position. 
     
     
       4. Device according to claim 3, wherein said blowing unit is turnable about the longitudinal axis thereof and fixable in position.